smallville ollie's wife Chloe was murdered. so hes not against killing.
oliver from arrow's girlfriend Laurel was murdered. so hes not against killing.
ollies at a warehouse of tony zuko(the guy who killed dick graysons parents) becuase he thinks hes responible. then oliver shows up for the same reason. they think the others responible.
The battle takes place in Nolans Batmans Gotham. both have lots of arrows becuase they thaught they be taking down gansters. they start at opposite sides of the warehouse